The cosmic microwave background exhibits spectral signatures and temperature anisotropies that suggest unexpected heating or energy injection in the early universe beyond what standard recombination physics predicts. Lambda-CDM struggles to explain localized temperature enhancements, unexplained heating signatures in the polarization data, and anomalies in the intensity-polarization cross-correlations that imply additional energy sources or non-standard ionization histories during the post-recombination epoch. The standard model lacks sufficient mechanisms to account for these heating signatures without invoking exotic physics or ad hoc modifications (Fixsen et al. 2009; Planck Collaboration 2018).